Thousands of strokes and heart attacks could be prevented if patients switched blood pressure pills.
Health records for five million with high blood pressure revealed the most popular pills, ACE inhibitors, were less effective than an alternative and caused more side effects.
The study in The Lancet estimates that changing to thiazide diuretics would prevent 15% of cardiovascular events.
There are 1.5 million such events, mainly heart attacks and strokes, every year in the UK.
High blood pressure is known as a “silent killer” as it does not have symptoms but puts strain on the blood vessels, heart, brain, kidneys and eyes. It affects over one third of adults in the UK.
The NHS has five types of drugs, costing between 30p and £1 a day, to treat blood pressure consistently above 140/90.
Other drug options are calcium blockers, which work by widening blood vessels, and diuretics, which flush excess water and salt from the body.
The study by Columbia University, New York, suggests if thiazide diuretics were prescribed straight away, then 3,100 heart attacks and strokes would have been prevented.
Author George Hripcsak said of looking at records from four countries: “We’ve found a way to fill in gaps left by randomised, controlled trials and help guide physicians in decision making.”
ACE inhibitors were the first drug prescribed to 48% of patients, compared with 17% prescribed thiazide diuretics.
Non-dihydropyridine calcium channel blockers were least effective as a first option, the study found.
